NAT router guidelines with Remote Desktop
Network Address Translation (NAT) networks (such as those that use macOS Internet Sharing) require special configuration.
If you want to use Remote Desktop to access a Task Server behind the NAT router, configure your NAT router to enable TCP and UDP port forwarding for ports 3283 and 5900. If you want to access clients behind the NAT router, forward unique TCP and UDP ports to all client computers behind the NAT router. In the example below, TCP and UDP ports 3284 and 5901 are forwarded to the client computer at 192.168.75.110.
When you add computers to a Remote Desktop computer list, add the addresses using the NAT router IP address and the forwarded port pairs. Add the IP address and port pairs for each computer located behind the NAT router.